Method of reducing ores and oxides



3 Sheets-Sheet 1 Jam J. H. STEWART METHOD OF REDUCING ORES AND OXIDES Filed Feb. 15, 1944 Oct. 2, 1945.

3 Sheets-Sheet 2 John [1 Stewart.

Oct. 2, 1945. J. H. STEWART METHOD Ol REDUCING ORES AND OXIDES Fil ed Feb. 15, 1944 Oct. 2, 1945. .J. H. STEWART 2,386,073

. I J f- METHOD OF REDUCING ORES AND OXIDES Filed Feb. 15,1944 3 Sheets-Shet s 2 I John Stewart v w, 9W

Patented on2, 1945 UNITED STATES PATENTOFFICE The invention relates broadly to the reduction of ores and oxides of metals and more particularly to the reduction of the various iron ores and oxides to produce sponge iron.

It is an object of the invention to provide for the reduction of ores or oxides by enclosing the same within a container formed from a reducing agent for said ores or oxides and subjecting the same to sufflcient temperature to reduce the ore or oxide.

A further object is to provide a novel method of reducing ores or oxides which consists in extruding, molding, casting or pressing a plastic mixture of the ore or oxide and a binder into a block, briquette, ball or the like and then enclosing the same within a container formedof a reducing agent and a binder and reducing the same by sufflcient temperature. a

Another object is to provide for the reduction of ores or oxides by molding or otherwise forming a container of a reducing agent and a binder, and placing therein a block, briquette or the like formed of the ore or oxide mixed with a binder,

and then submitting the same to proper temperquette, ball or the like of a mixture of the ore or 1 Still another object of the invention is the pro vision of a process for the reduction of the natural iron ores such as hematite, linronite, magnetite,

oxide and a binder and then dipping it repeatedly I if necessary or desirable, into a slurry composed of'a reducing agent and a binder, and then sub- J'ecting it to sufiicient temperature to reduce the ore or oxide.

A further object is the provision of a method for reducing ores or oxides which consists in forming a ball of a mixture of the ore or oxide and then rolling the ball around in a plastic mixture of a reducing agent and a binder to form a covering thereof around the ball, and then reducing the ore or oxide by heat. 7

A still further object is the provision of a method. for reducing ores or oxides by forming a block, briquette or the like of a mixture of the ore or oxide and a binder and then molding or casting a covering of a reducing agent and a binder around the same, and then reducing the ore or oxide by heat.

Another object is to enclose an ore or oxide within a container or covering of a reducing agent and a binder in any of the ways above referred to and to then apply an incombustible coating of an I ,air setting refractory cement such as silicate of soda with or without raw and calcined clay to the exterior of the container or covering, after which the ore or oxide is reduced by heat.

siderite, gothite and tungite, bog ores and the like,

or iron oxides such as mill scale, flue dust or other materials containing appreciable amounts of ferric oxide (FezOa), ferroso-ferric oxide (F6304) or ferrous oxide (FeO), which consists in enclosing the iron ore or oxide in a container or coverin composed of carbonaceous material and a binder and preferably including a small amount of lime, and subjecting the same to a sufliciently high temperature for a sufficient period of time to reduce the ore or oxide.

Affurther object is the provision of a process for reducing iron ores or oxides which consists in forming blocks, briquettes, balls or the like from iron ores or oxides mixed with a binder, such as container, or covering, as by spraying, dipping or painting, and then subjecting it to a high tern perature for a'sufilcient time to reduce the iron ore or oxide.

The above objects together with others which will be apparent from the drawings and following description, or which may be later referred to.

may be attained by carrying out the process in the manner hereinafter describedin detail, reference being made to the accompanying drawings, in which: v

Figure 1 is a perspective view of a block or briquette formed of ore or oxide and a binder;

Fig. 2 a perspective view of a container formed of a reducing ageni'tsuch as powdered carbonaceous material and a binder, such as clay;

Fig. 3 a side elevation of the container with a film or coating of an airsetting refractory cement-such as silicate of soda and raw and calcined clay on the exterior thereof.

Fig. 4 a vertical sectional view through a plurality of the reducing agent containers with the ore or oxide therein, showing the manner in which they are stacked in a kiln or furnace.

Fig. 5a sectional view through a two piece mold showing the manner in which a covering of reducing agent and binder may be molded, cast or ide.

Fig. 6 a sectional view showing the manner in which a block or briquette of ore or oxide may be provided with a covering by dipping into a slurry formed of reducing agent and binder;

Fig. 7 a perspective view of one member of a two part container or covering formed of reducing agent and binder;

Fig. 8 a sectional view showing the manner in which a block or briquette of ore or oxide may be enclosed in the two part container;

Fig. 9 a plan view showing the manner in which a plurality of the two part containers, with blocks or briquettes therein, may be placed in a kiln or furnace for reduction;

Fig. 10 an elevation of a ball of ore or oxide.

Fig. 11 a sectional view of theball with'a cov.- ering of reducing agent andxbinder applied thereto as by rolling the ball in a plastic mixture of reducing agent and binder, and

Fig. 12 a vertical, sectional view through a kiln showing the manner in which the reducing agent containers shown in Figs. 2 to 4, with the ore or oxide therein, are placed in the kiln.

Referring first to Figs. 1 to 4 inclusive and Fig. l2, in carrying out the improved process, a block or briquette I may be formed from a mixture of the ore or oxide to be reduced and'a suitable binder. The process is adapted for the reduction of various metal ores and oxides but it is more especially concerned with the reduction of iron ores or oxides for the production of sponge iron.

Any of the well known natural iron ores such as hematite, limonite, magnetite, siderite, gothite, tungite, etc., or any iron oxide such as mill scale, flue dust or other material containing ferric oxide (F6203), ferroso-ferric oxide (FeaOa) or ferrous oxide (FeO), may be reduced to sponge iron by this process.

A sufficient amount of a suitable binder is mixed with the ore, in cases where an additional binder is necessary, although where the ore is sufficiently plastic or colloidal no additional binder may be required, and it should be understood that where ore or oxide anda binder are referred to herein, the binder may be contained in the ore, or added thereto. Where iron ores areused, a small amount of starch has been found to make a very satisfactory binder. A 7 starch solution has given very satisfactory results. A sufllpressed around a block or briquette of ore or oxcient amount of the starch to bind the particles together is mixed with finely divided ore and the same may be extruded, pressed, or cast to form a block or briquette as indicated at I5. This block or briquette is dried and then may be placed in a container as indicated generally at l6 which is formed of a mixture of a reducing agent and suflicient binder to hold the same together.

For the reduction of iron ores or oxides, the reducing agent may be a carbonaceous material, such as powdered coal, either anthracite or bituminous, or powdered coke mixed with a small amount of clay for binder, and preferably containing a small. amount of lime to assist in removing sulphur.

The container may be made from a mixture containing about 100 parts of powdered coke or coal, sufiicient clay to form a binder and from 3 to 10 parts of lime. Very good results have been obtained by using 100 parts of powdered coke, 5 llzarts of bentonite or other clay and 10parts of The container may be formed by pressing, mol ing, casting or extruding the mixture to form a container as indicated at l6, having the central opening I! of suflicient size to snugly receive the block or briquette I5 of ore 0r oxide. In case the containers are formed 'with an upper open end,

as shown in the drawings, and arranged .to be stacked one 'upon another, as shown in Figs. 4 and 12, so that each container closes the top of the next lower container, the bottom wall I8 of each container may be considerably thicker than the side walls l9.

In order to hold the reducing gases, produced by heating the reducing agent container, within the container and cause them to penetrate the ore or oxide therein, an incombustible film to prevent oxidizing of the carbon in the container, which may be an air setting refractory cement such as silicate of soda to which may be added raw and calcined clay, as indicated at 20, may be applied to the exterior of the container by sprayin dipping or painting with a liquid solution of such material.

If desired, instead of forming a block or briquette of the ore mixed with a binder, loose particles of finely divided ore may be placed in the container, madeas above described, filling the container. The containers may be stacked one upon the other within a kiln or furnace as shown in Fig. 12 and the uppermost container of each tier covered with a slab or plate of the same material as indicated at 2|, and the kiln may be operated at a high temperature for suflicient time to reduce the ore or oxide in the containers.

In reducing iron ores or oxides the kiln may be brought up to and maintained at a high temperature, and during this time as the carbonaceous containers are heated, they will generate or evolve carbonaceous gases or vapors which are passed through the ore or oxide contained therein, reducing the same. The kiln or furnace may be maintained under reducing atmosphere although this is not necessary since the ore or oxide is enclosed within the carbonaceous container so that it is maintained under reducing atmosphere.

The time required for such reduction of the ores or oxides will vary somewhat with the size of the charge, the degree of heat, the nature and fineness of the ore, etc., but at a temperature of about 2000 F. the ore or oxide will be reduced within a period of between 4 and 5 hours, producing a block or briquette of sponge iron.

After the reduction process, the materials are allowed to cool sufliciently to be handled after which the containers or covering may be removed leaving substantially solid blocks or briquettes of sponge iron. Where loose ore is placed in the containers, instead of the blocks or briquettes of ore or oxide, the resulting reduced product is of a more porous nature.

Instead of forming a container such as shown in Figs. 2 to 4 to receive the block or briquette of ore or oxide,'a covering of carbonaceous material and binder may be cast, molded, or pressed around the block or briquette as shown in Fig. 5. For this purpose a two part mold preferably of plaster of Paris indicated at 2|, may be used, the block or briquette l5 being placed within one half of the mold and spaced from the bottom by chaplets 22 and the mixture of finely divided carbonaceous material, binder, and if desired, lime, as indicated at 23 may be introduced as a slurry and cast, molded, or pressed around the block or briquette by means of the mold members 2|. The plaster molds will quickly absorb the moisture from the slurry so that the molded article may be quickly removed and handled.

5. The process of reducing iron oxides which The ore or oxide thus provided with the covering of reducing agent may then be placed in a kiln'or furnace and reduced in the manner above described.

If desired the block or briquette of ore or oxide may be coated with a covering of carbonaceous reducing material by dipping it repeatedly, if necessary, into a slurry formed of powdered coal or coke, a binder and if desired, small amount of lime, until a covering of suflicient thickness of the carbonaceous reducing material is built up around the exterior of the block or briquette as indicated at 21 in Fig. 6. A film of silicate of soda or the like as indicated at 25 may then be applied to the exterior of the covering and the-process may be carried out as above described.

Instead of making the carbonaceous container in a single piece as shown in Figs. 2 to 4, each container may be made up of two similar halves of angle construction as shown at 26 in Fig. '7 the two halves being placed together around the ore or oxide block or briquette I5 as shown in Fig. 8 and the enclosed blocks or briquettes may then be placed end to end in a kiln or furnace as shown in Fig. 9, the endmost ones being closed as by a slab or plate 21. t

As shown in Fig. 10 the ore or oxide and binder may be rolled or formed into a ball as indicated at 28 which may be rolled around in a plastic mixture of carbonaceous reducing material until it is built up to form a covering thereon as shown at 29 in Fig. 11. After the same is dried it may ing container and enclosed oxides to suflicient heat to generate reducing gases within the conbe coated with a film of silicate of soda orfeldplished exclusively by the reducing agent in the container.

2. The process of reducing iron oxides which consists in enclosing oxides in a container formed of a carbonaceous reducing agent and a binder, coating the exterior of the container with an airtight film of'incombustible material and subjecting the container and enclosed oxides to sufficient heat to generate reducing gases within the container said reduction being accomplished exclusively by the reducing agent in the container.

tainer said reduction being accomplished exclusively by the reducing agent in the container.

6. The process of reducing iron oxides which consists in forming a block, of finely divided oxide and a binder, enclosing the same in a covering or container formed of finely divided carbonaceous material and a binder, and subjecting the carbonaceous covering and enclosed block, of oxide to sufllcient heat to generate reducing gases within the container said reduction being accomplished exclusively by the reducing agent in the container.

7. The process of reducing iron oxides which consists in forming a block, of finely divided oxide and a binder, enclosing the same in a covering or container formed of finely divided carbonaceous material and a binder, coating the exterior of the covering orv container with an airtight film of incombustiblematerial, and subjecting the carbonaceous covering and enclosed block, of oxide to sufiicient heat to generate reducing gases within the container said reduction being accomplished exclusively by the reducing agent in the container.

8. The process of reducing iron oxides which consists in forming a block, of finely divided oxide and a binder, enclosing the same in a covering or container formed of finely divided carbonaceous material and a binder, coating the exterior of the covering or-container with a film of silicate of soda and raw and calcined clay and subjecting the carbonaceous covering and enclosed block, of

40 oxide to suflicient heat to generate reducing gases 3. The process of reducing iron oxides which consists in enclosing oxides in a container formed of a carbonaceous reducing agent and a binder, coating the exterior of the container with a film of silicate of soda and subjecting the container and enclosed oxides to suflicient heat to generate reducing gases within the container said reduction being accomplished exclusively by the reducing agent in the container.

4. The process of reducing iron oxides which consists in enclosing oxides in a container formed of a carbonaceous reducing agent and a binder, coating the exterior of the container with a film of silicate of soda and raw and calcined clays and subjecting the container and enclosed oxides to suflicient heat to generate reducing gases within the container said reduction being accomplished exclusively by the reducing agent in the container. 7

within the container said reduction being accomplished exclusively by the reducing agent in the container.

9. The process of reducing iron oxides which consists in forming a block, of finely divided oxide and a binder, dipping the same into a slurry formed of finely divided carbonaceous material and a binder to form a covering thereon, and subjecting the covered block, of oxide to sufficient heat to generate carbonaceous reducing gases within the covering said reduction being accomplished exclusively by the reducing agent in the covering.

10. The process of reducing iron oxides which consists in forming a block, of finely divided oxide and a binder, dipping the same into a slurry formed of finely divided carbonaceous material and a binder-to form a covering therein, coating the covering with a film of silicate of soda and raw and calcined clay and subjecting the covered block, of oxide to sufficient heat to generate reducing gases within the covering said reduction being accomplished exclusively by the reducing agent in the covering.

11. The process of reducing iron oxides which consists in forming a block, of finely divided oxide and a binder, forming thereon a covering of finely divided carbonaceous material and a binder, and subjecting the covered block, to suflicient heat to generate reducing gases within the covering said reduction being accomplished exclusively by the reducing agent in the covering.

12. Th process of reducing iron oxides which consists in forming a block, of finely divided oxide and a binder, forming thereon a covering 01 finely i the covering.

13. The process of reducing iron oxides which consists in forming a ball of finely divided oxide and a binder, rolling said ball around in a plastic mixture of finely divided carbonaceous material and a binder to form a covering thereof upon the ball, and subjecting the covered ball to sufficient heat to generate reducing gases within the covering said reduction being accomplished exclusively by the reducing agent in the covering.

14. The process of reducing iron oxides which consists in forming a ball of finely divided oxides and a binder, rolling said ball around in a plastic mixture of finely divided carbonaceous material and a, binder to form a covering thereof upon the ball, coating the covering with a film of silicate of soda and raw and calcined clay and subjecting the covered ball to sufiicient heat to generate reducing gases within the covering said reduction being accomplished exclusively by the reducing agent in the covering.

15. The process of making sponge iron from ironoxides which consists in forming a block from a mixture of finely divided iron oxide and a *binder, forming a container from a mixture of heat to generate reducing gases within the container said reduction being accomplished exclusively by the reducing agent in the container.

16. The process of making sponge iron from iron oxides which consists in forming a block from a mixture of finely divided iron oxide and a binder, forming a container from a mixture of 5 finely divided carbonaceous material, a small.

amount of clay and a small amount of lime, placing the block of iron oxide within the container, coating the exterior of the container with a film of silicate of soda and raw and calcined clay and subjecting it to sumcient heat to generate reducing gases within the container, said reduction being accomplished exclusively by the reducing agent in the container.

17. The process of making sponge iron from iron oxides which consists in forming-a block of placing the block within the container and subjecting it to about 2000 F. for a period of at least four to five hours said reduction being accomplished exclusively by the reducing agent in the container.

18. The process of making sponge iron from iron oxide which consists in forming a block of finely divided iron oxide and starch, forming a container of a mixture of about parts powdered carbonaceous material, about 5 parts of bentonite clay and from 3 to 10 parts of lime, placing the block within the container, coating the exterior of the container with a film of silicate of soda and raw and calcined clay and subjecting it to about 2000 F. for a period of at least four to five hours said reduction being accomplished exclusively by the reducing agent in the container.

JOHN H. STEWART. 

